Counterbalance for motor-shafts.



1. w. RIDGWAY.

COUNTERBALANCE FOR MOTOR SHAFTS.

APPLICATION HLED JULY I7. 1916- nl.:

Patented Apr. 11,1917.

2 SHEETS-SHEET 2.

" UNITED IsrA'riis initrniafr OFFICE.

Joslin; W. RIDGWAY, orv noire ISLAND CITY, NEW YORK.

COUNTERBALANCE FOR MOTOR-SAFTS.

Y tion at a highfrate; of speed, such as may be obtained, for instance, with the engines of self-propelled vehicles or similar machines.

It is now universally understood among mechanical engineers that there are unbalanced forces inherent or developed in plural-cylinder engines which must be counteracted in order to insure safe and smooth running thereof when running be` yond a certain velocity. The inertia and centrifugal force of each crank arm and crank pin are to be taken into consideration and compensatedfor, as they exert distortive strains uponv the engine shaft, if not counterbalanced by suitably distributed weights. The ponderal distribution, how ever, involves more than placing the cranks in static balance, as they shouldbe in running balance as well. This being recognized, the custom has arisen to counteract the unbalanced centrifugal forces by opposing thereto similar forces applied .to the crankshaft as nearly as possiblein the saine radial plane. But the remedy thereby af,

forded is not satisfactorily effective, for the reason that, while the centrifugal forces to be balanced act radiallyl to` the `axis of revolution, their resultant is a tendency to, yangular 'motion relatively to the radial plane. In view of the foregoing, the' present invention has for its primary object to provide aiiovel, simple and eicient method and means of counteraeting thelack of running balance in the pluralthrow crankshaft of the type above mentioned, yincluding such parts of the connecting-rods asvmay' revolve' with the crankshaft.

Another object ofthe invention is so to eiiect the balancing of forces that the strains on the shaft attachmentsv will be limited to those generating rotativemotion'.

Other objects and advantages of the invention will in part be obvious and in part be described in the specification.

Svpecication of Letters fatent.

equipment in section;

Patented Apr'. 17, 1917..

Application filed July `17, 1.916. Serial 17o. 199,864.

Reference will now be Ymade to the accompanying drawings, in two sheets, for a de-V tailed description of a few of the most approved forms of the invention, as applied to y crank-shafts of motors having several cylinders.

In the said drawings,

Figure 1 is a side view of a three-bearing, four-throw crankshaft counterbalanced in the manner provided for by the invention, part thereof being in sectional elevation; i

- Fig. 2 is a vertical transverse section on the line 2 2 of Fig. 1, looking toward the left, in the direction indicated by the arrows; Fig. 3 'is a partly-sectioned side elevation of a similarly equipped crankshaft, illus trating a slightly different mode of constriicA tion;

Fig. 4 is a vertical section taken at right angles to the latter view, again looking to f the left, along the line 4 4;

Fig. 5 is a side elevation, partly in section, representing` a two bearing, lfour 1 throw crankshaft to which is attached one of the simplest forms of the invention;

Fig. 6 is a transverse section taken vertiiy cally along the line 6 6 of the preceding view, exposing the left-hand portion thereof;

Fig. 7 illustrates another modified embodiment of the invention, applied to a two-bears ing, four-throw crankshaft, thelatter being shown in side elevation, with part of its Fig. 8 isan upright section on the line 8 8 of Fig. 7, looking toward the left; and

Figs. 9, v10 and 11 are diagrams, respecy tively intended to depict the directionY followed by the centrifugal forces, as generated ineach instance, first, in the ordinary crankshaft; secondly, in a crankshaft provided with the customary COunterWeghtS; and, thirdly, in a crankshaft wherewith the ,present invention has been incorporated.

.Referring now in detail to the drawings,

journals 21, 22 and 23, respectively, ogf the ioo different forms of crankshafts represented 5 in the drawings hereto annexed are alined in the usual manner and severally fitted in their bearings (not shown). Three-suchl journals, it will be observed, are illustrated in Figs. l and 3, whereas only 'two appear in Figs. 5 and 7, as also ,in the diagrams 9, l0 and 11.

Crank arms26, 27, of unequal lengths, are

formed' on the various crankshafts, accordparticular quantity or grouping of the elements here enumerated. In the diagrams, Figs. 9, 10 and l1 a single long arm is indicated. This is suiiicient to denote that, pursuant to recognized usage, the long arms 26,

whether one or more, are located intermediately of the short arms 27 next adjoining the main bearings or journals 21 and 22 of the several crankshafts. The joints or bearing portions of the crank pins, where the connecting-.rods (not shown) grasp the same,

are indicated by the reference numeral 29.

Referring more particularly to the said diagrams, it will be observed, first, that an ordinary crankshaft having main bearings 21, 22, and oppositely extended crank arms 27, 26, 27 with interconnecting crank pins, as outlined in. Fig. 9, is in static balance, when at rest, assuming that the several parts have been correctly proportioned. But, when revolving at high velocity, the planes of' revolution of the parts assembled at 29 will be as the arrows 30, and the centrifugal forces developed will trend in like directions, because 'the weight of each group of parts 29 is not symmetrically disposed on opposite slides of its own plane, and the respective lanes in which the two groups revolve, libing separated, naturally do not coincide; The resultant of the centrifugal forces acting in the two planes named is a tendency of the parts or masses 29 to travel in the opposed ydirections indicated by the arrows 31, that is, both toward a median plane coinciding with that of the longA arm 26 in the said Fig. 9. Consequently, the crankshaft is subjected to more or less distortion and vibration, with obvious injury to the crank pins and connecting rods, according to the speed at which it revolves.

The method heretofore adopted to balance a crankshaft of the type represented in the preceding diagram is shown diagrammatically in Fig. 10.' This method consists in effecting an even distribution of the masses on opposite sides of each plane of `revolution, by attaching to the crankshaft a certain number of additional arms and weights, as 34 and 35. The centrifugal forces to be balanced and the countoracting forces generated by the balancing VarmeI and weights are indicated by the, arrows QQ and 37. This may properly be called antincenvenie'nt, expensive, ,and inadquate method of remedying the defect in the running balance of a crankshaft, as above enunciated.

No eXtra arms are added to the crankshaft, in carrying out the present invention, and only such counterweights are employed as have been ascertained to be strictly requisite to bring the respective planes of revolution of the masses lto a common center. This is accomplished by attaching weights to the long arms ofthe crankshaft on the sides-remote from their crankpins, so that the tendency of movement of the revolving weights will be toward a central plane, where it will nullify the similar tendency of the pins and connecting rods to move in the opposed di,- rection. As diagrammed in Fig. l1, a weight 41,' placed at each end of the long arm 26, onthe opposite side from the crank pin 28, will develop upon being rapidly revolved centrifugal forces trending in the direction of the arrows 42', which .result in forces trending in the direction of the arrow 43, which forces immediately encounter and alance those traveling in the direction of the arrow 31 and generated by the mass 29 adjacent to the said weight. This exemplifies the principle upon which the invention is based. a

A convenient method of weighting a long arm on a crankshaft, in accordance with the said principle, is to place a ring obliquely around the arm, as represented in Figs. 1 to 8 of the drawings. Such a ring may be attached to the arm and the form or structure thereof varied in numerous ways, as will presently be explained.

As shown in Figs. 1 and 2, a ring 46, of uniform cross-section throughout lts circumference, is made to surround approximately one-half the width of each long arm 26, on opposite sides of the arms center,

which in the present instance coincides with the center of the shafts bearinffs or journals 21, '22 and 23. AThe ring is o -set centrally, as at 47, so that it will cross the arm (either arm 26 to which it is applied) and throw its weight on the side thereof remote from the crank pin 28, at each end of-the arm. To keep it in place, the ring is provided with lugs 48, arranged to bear against the ends of the arm on the sides away from the crank pins, and boltedthereto, as at 49.

A similar construction is illustrated in Figs. 3 and 4, where the long -arms 26 of the crankshaft appear as {being equipped each with a ring 46, offset at 47, and having inwardly-projecting lugs 48, adapted to receive bolts 49, all as above described. In the latter-named `figures, however, the ring is further projectin flanges or stops 51, designed to bear on t 1e ends of the corresponding long arm 26, directly opposite each crank pin 282 It will be noted that the stops 51 are respecprovided with a pair of inwardly-"` nated by the same reference numerals, with the exception of the ring 54, which has no central offset. But this ring is positioned obliquely with relation to the long arm 26, as in all other instances.

In Figs. 7 and 8, the ring above referred to is replaced by an equivalent structure,'

composed of two segmental weights 56, 57, united by tie-rods 58, 59, at the opposite ends thereof. As shown, the segmental weights are disposed transversely to the ends of the long arms -26 of the crankshaft, on the sides remote from the' crank pins 28. The weights are formed with angular recesses 60 .therein in order that said weights may abut squarely against their respective' ends of the long arms, and bolts 61, or similar fastenings, are employed .to holdv the parts in their relative positions. It will be readily perceived that the invention herein disclosed provides a novel system of balancing crank-shafts which possesses several advantages of a practical character. Thus, the system affords an easy,y

economical,I and secure method of fastening balance weights.` The counterweights used are inexpensive, and a couple, only is needed to balance a crankshaft having four throws. And, for example, as applied, the `weights are more effective as fly wheels than the usual type of balance weights. In constructions based on the prior art, the balancing forces exert a radial stress on the crankshaft, but in this improved construction they produce a stress which acts at an angle to the radial plane. In other words, the balancing forces, in the older constructions, act at right angles to the axisof revolution, whereas in the present construction they act parallel to the axis of revolution.

The invention in its broader aspects is not limited to the precise construction shown and described nor to any particular construction by which Vthe same may be carried into effect, as many changes may be made in the details thereof Without departing from` the main principles of the invention `or sacricing .its chief advantages. Thus, in the foregoing description it has been assumed that all the parts of the crank lshaft arrangement are in static balance 'or 'equilibrium so that the counterbalancing 'rings or segmentsv have been shown and described as applied symmetrically to the crank armsor concentricallv to the axis of rotation of the` crankshaft; but, it will be obvious that were the crank arrangement different, e. g., out of static balance, this condition might readily be provided for by varying the"form o r disposition of the counterbalancing rings or weights to correspond, without affecting the' principle and mode of operation previously set forth.

- I claim: ,Y

1. The combination with` a crankshaft -arm having crank pins projecting respectively from the end sthereof in opposite directions, of weights connected with said arm onthe sides remote from said crank pins.

v2. The combination with a crankshaft-arm formed with crank pins projecting laterally therefrom at or near its ends, of weights opposed to said crank pins connected with one another transversely of said arm.

3. The combination with a crankshaft arm having pins projecting oppositely from the sidesthereof one at each end, of Weights attached 'to both ends of 4said armv soas to re` volve therewith in a plane bisecting a line drawn through the mass centers of said pins.

4. The combination with a crankshaft arm having pins projecting from the yends thereof one at each side, of a ring disposed about said armsov as to throw its Weight thereon oppositely to said pins in substantially equal parts on the remote sides.

5. The combination with acrankshaft, an arm thereacross, and pins projecting laterally one from each end of said arm, of a ring concentric with said crankshaft encircling the latter and the arm in an oblique direction.

6; The combination with a crankshaft, an arm transverse thereto, and oppositely projecting pins at the ends of said arm, of a ring around the arm offset to vdivide the mass thereof remotely from said pins on opposite sides of the plane of revolution.-

7 The combination with a crankshaft, an arm extending transversely thereof, and pins projecting laterally from said arm at opposite ends, of a. ring obliquelyencompassing the arm, abutments on said ring arranged to bear against both ends of the arm on sides thereof removtefrom said pins, and means for fastening said ends of the arm to Said abutments each ata distance from the crankshaft.

8. The combination with a crankshaft armv arm having pins projecting respectively from the ends thereof in' op osite directions,V of weights disposed rela/tive y to said arm in iso such manner that the balancing Vstresses afhaving a plurality of arms extending therefrom, of weights so arranged .in relation to said arms that the balancing stresses a'ect "the crankshaft' partlyl on lines at an angle t0 the axis thereof and partly on lines paral- Y 12. Thercombination with aferankshaft weighted for static balance, a transversely disposed arm thereon, and pins projecting laterally from said arm, one at each end, of

a ringl.set around the arm so as to divide the mass thereof remotely said pins on opposite sides of the plane' of revolution.

18. The combination with a lural-throw crankshaft having arms providldd with pitman connections, of balancing Weights arranged to bear 0n said arms at the sides thereof remote from said connections.

14. The-combination with a plural-throw crankshaft having arms provided With c0nneeting-rod retainers, of balancing Weights functioned to revolve with said arms at the sides thereof remote from said retainers.

In testimony whereof, I have signed my name to this specification.

JOSEPH W. RIDGWAY. 

